Alcoholic Hepatitis: Lost in Translation

Identification of hepatic fibrosis inhibitors through morphometry analysis of a hepatic multicellular spheroids model

A chronic, local inflammatory milieu can cause tissue fibrosis that results in epithelial-to-mesenchymal transition (EMT), endothelial-to-mesenchymal transition (EndMT), increased abundance of fibroblasts, and further acceleration of fibrosis. In this study, we aimed to identify potential mechanisms and inhibitors of fibrosis using 3D model-based phenotypic screening. We established liver fibrosis models using multicellular tumor spheroids (MCTSs) composed of hepatocellular carcinoma (HCC) and stromal cells such as fibroblasts (WI38), hepatic stellate cells (LX2), and endothelial cells (HUVEC) seeded at constant ratios. Through high-throughput screening of FDA-approved drugs, we identified retinoic acid and forskolin as candidates to attenuate the compactness of MCTSs as well as inhibit the expression of ECM-related proteins. Additionally, retinoic acid and forskolin induced reprogramming of fibroblast and cancer stem cells in the HCC microenvironment. Of interest, retinoic acid and forskolin had anti-fibrosis effects by decreasing expression of α-SMA and F-actin in LX2 cells and HUVEC cells. Moreover, when sorafenib was added along with retinoic acid and forskolin, apoptosis was increased, suggesting that anti-fibrosis drugs may improve tissue penetration to support the efficacy of anti-cancer drugs. Collectively, these findings support the potential utility of morphometric analyses of hepatic multicellular spheroid models in the development of new drugs with novel mechanisms for the treatment of hepatic fibrosis and HCCs.

PDK2: An Underappreciated Regulator of Liver Metabolism

Pyruvate metabolism is critical for all mammalian cells. The pyruvate dehydrogenase complex couples the pyruvate formed as the primary product of glycolysis to the formation of acetyl-CoA required as the primary substrate of the citric acid cycle. Dysregulation of this coupling contributes to alterations in metabolic flexibility in obesity, diabetes, cancer, and more. The pyruvate dehydrogenase kinase family of isozymes phosphorylate and inactive the pyruvate dehydrogenase complex in the mitochondria. This function makes them critical mediators of mitochondrial metabolism and drug targets in a number of disease states. The liver expresses multiple PDKs, predominantly PDK1 and PDK2 in the fed state and PDK1, PDK2, and PDK4 in the starved and diabetic states. PDK4 undergoes substantial transcriptional regulation in response to a diverse array of stimuli in most tissues. PDK2 has received less attention than PDK4 potentially due to the dramatic changes in transcriptional gene regulation. However, PDK2 is more responsive than the other PDKs to feedforward and feedback regulation by substrates and products of the pyruvate dehydrogenase complex. Although underappreciated, this makes PDK2 particularly important for the minute-to-minute fine control of the pyruvate dehydrogenase complex and a major contributor to metabolic flexibility. The purpose of this review is to characterize the underappreciated role of PDK2 in liver metabolism. We will focus on known biological actions and physiological roles as well as what roles PDK2 may play in disease states. We will also define current inhibitors and address their potential as therapeutic agents in the future.

Alcoholic hepatitis and metabolic disturbance in female mice: a more tractable model than Nrf2-/- animals

Alcoholic hepatitis (AH) is the dramatic acute presentation of alcoholic liver disease, with a 15% mortality rate within 28 days in severe cases. Research into AH has been hampered by the lack of effective and reproducible murine models that can be operated under different regulatory frameworks internationally. The liquid Lieber-deCarli (LdC) diet has been used as a means of ad libitum delivery of alcohol but without any additional insult, and is associated with relatively mild liver injury. The transcription factor nuclear factor-erythroid 2-related factor 2 (Nrf2) protects against oxidative stress, and mice deficient in this molecule are suggested to be more sensitive to alcohol-induced injury. We have established a novel model of AH in mice and compared the nature of liver injury in C57/BL6 wild-type (WT) versus Nrf2-/- mice. Our data showed that both WT and Nrf2-/- mice demonstrate robust weight loss, and an increase in serum transaminase, steatosis and hepatic inflammation when exposed to diet and ethanol. This is accompanied by an increase in peripheral blood and hepatic myeloid cell populations, fibrogenic response and compensatory hepatocyte regeneration. We also noted characteristic disturbances in hepatic carbohydrate and lipid metabolism. Importantly, use of Nrf2-/- mice did not increase hepatic injury responses in our hands, and female WT mice exhibited a more-reproducible response. Thus, we have demonstrated that this simple murine model of AH can be used to induce an injury that recreates many of the key human features of AH - without the need for challenging surgical procedures to administer ethanol. This will be valuable for understanding of the pathogenesis of AH, for testing new therapeutic treatments or devising metabolic approaches to manage patients whilst in medical care.This article has an associated First Person interview with the joint first authors of the paper.

Keratin 18 Is a Diagnostic and Prognostic Factor for Acute Alcoholic Hepatitis

BACKGROUND & AIMS

Acute alcoholic hepatitis (AAH) is a major cause of liver-related morbidity and mortality; there are no good blood biomarkers for diagnosis or determining magnitude of cell death. Keratin 18 (KRT18, also called K18), found in epithelial cells, is released from hepatocytes upon death. We investigated whether level of K18 is a better marker of hepatocyte death than standard biomarkers and might be used to identify patients with AAH at risk for death within 90 days.

METHODS

We analyzed data from 173 participants in a large trial performed at 4 medical centers. Participants with AAH were classified as severe (n = 57, model for end-stage liver disease [MELD] scores above 20) or moderate (n = 27, MELD scores from 12 to 19); 38 participants had alcohol use disorder with mild (n = 28) or no liver injury (n = 10); 34 participants had nonalcoholic steatohepatitis; and 17 participants were healthy (controls). We quantified serum levels of K18 using ELISAs and APOPTOSENSE kits.

RESULTS

Serum level of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and the ratio of AST:ALT did not correlate with MELD scores. Patients with alcohol use disorder had higher serum levels of ALT than patients with severe AAH. Levels of K18M65 and K18M30 had statistically significant increases as liver disease worsened, as did the degree of necrosis (ratio of K18 M65:M30). The ratio of K18M65:ALT was increased in serum from patients with AAH compared with controls. Serum levels of K18 identified patients who died within 90 days with greater accuracy than commonly used static biomarkers.

CONCLUSIONS

There is a stronger association between serum level of keratin 18 and amount of hepatocyte death and liver disease severity than for other biomarkers (AST, ALT, and the AST:ALT ratio). The ratio of K18M65:M30 might be used as marker of mechanism of hepatocyte death, and the ratio of K18M65:ALT might be used to distinguish patients with AAH from patients with nonalcoholic steatohepatitis. Serum levels of K18 might be used to identify patients with severe AAH at risk for death. ClinicalTrials.gov identifier # NCT01922895 and NCT01809132.

Outcomes and Toxicology of Herbal Drugs in Alcoholic Hepatitis - A Single Center Experience from India

Background and Aims: We aimed to study clinical outcomes and liver biopsy features of alcoholic hepatitis (AH) patients on complementary and alternative medicines (CAMs) and to analyze the retrieved drugs for chemical and toxic components linked to drug-induced liver injury. Methods: We retrospectively assessed clinical, biochemical and liver biopsy features of AH patients on CAM with drug-induced liver injury (AH-CAM, n = 27) and compared them to a control group (classical AH, n = 29) on standard of care. Patients without liver biopsy evaluation and other causes for liver disease were excluded. Samples of the CAMs (n = 42) from patients were retrieved and assessed for chemical and toxins. Results: All were males, and significantly worse clinical presentation, biochemical severity, and liver disease scores were notable in patients with AH-CAM. Traditional Ayurvedic-polyherbal formulations were the most commonly used CAM. On liver histology, varying grades of severe-necrosis, severe hepatocellular, canalicular, cholangiolar cholestasis with predominant lymphocytic-portal-inflammation and varying grades of interface-hepatitis were noted in AH-CAM. Analysis of CAMs revealed presence of heavy metals up to 100,000 times above detectable range and adulterants, such as antibiotics, chemotherapy agents, nonsteroidal anti-inflammatory drugs, alcohols, antidepressants, anxiolytics, and recreational drugs. On follow up, a significantly higher number of patients with AH on CAM died at end of 1, 3- and-6-months compared to controls (37% vs. 83%, 29% vs. 62%, 18% vs. 52% respectively; p < 0.001). Conclusions: Patients with AH and CAM-related drug-induced liver injury have extremely poor short-term survival in the absence of liver transplantation compared to those patients with AH on evidence-based management. Early transplant referral and educating on and curbing of CAM use in severe liver disease through strict monitoring of unregulated traditional health practices can help ease the burden of liver-related death.

Cellular Abnormalities and Emerging Biomarkers in Alcohol-Associated Liver Disease

Alcohol-associated liver disease (AALD) is the third most common preventable cause for disease burden and mortality in the US. AALD, including alcoholic hepatitis (AH), contributes to half of admissions from decompensated liver disease and 20% of all liver transplants in the US. Peripheral blood cells contribute to systemic inflammation, oxidative stress, mitochondrial dysfunction, and fibrosis in AALD and AH. Alcohol dysregulates function of lymphocytes, neutrophils, monocytes, and tissue macrophages of the innate immune system. These alterations in turn can modulate adaptive immune responses. In this review, we describe these disruptive effects of alcohol on cells of the innate and adaptive immune system and focus on cellular-based emerging biomarkers on diagnosis and prognosis of patients with AALD and AH.

Alcoholic Liver Disease: Alcohol Metabolism, Cascade of Molecular Mechanisms, Cellular Targets, and Clinical Aspects

Alcoholic liver disease is the result of cascade events, which clinically first lead to alcoholic fatty liver, and then mostly via alcoholic steatohepatitis or alcoholic hepatitis potentially to cirrhosis and hepatocellular carcinoma. Pathogenetic events are linked to the metabolism of ethanol and acetaldehyde as its first oxidation product generated via hepatic alcohol dehydrogenase (ADH) and the microsomal ethanol-oxidizing system (MEOS), which depends on cytochrome P450 2E1 (CYP 2E1), and is inducible by chronic alcohol use. MEOS induction accelerates the metabolism of ethanol to acetaldehyde that facilitates organ injury including the liver, and it produces via CYP 2E1 many reactive oxygen species (ROS) such as ethoxy radical, hydroxyethyl radical, acetyl radical, singlet radical, superoxide radical, hydrogen peroxide, hydroxyl radical, alkoxyl radical, and peroxyl radical. These attack hepatocytes, Kupffer cells, stellate cells, and liver sinusoidal endothelial cells, and their signaling mediators such as interleukins, interferons, and growth factors, help to initiate liver injury including fibrosis and cirrhosis in susceptible individuals with specific risk factors. Through CYP 2E1-dependent ROS, more evidence is emerging that alcohol generates lipid peroxides and modifies the intestinal microbiome, thereby stimulating actions of endotoxins produced by intestinal bacteria; lipid peroxides and endotoxins are potential causes that are involved in alcoholic liver injury. Alcohol modifies SIRT1 (Sirtuin-1; derived from Silent mating type Information Regulation) and SIRT2, and most importantly, the innate and adapted immune systems, which may explain the individual differences of injury susceptibility. Metabolic pathways are also influenced by circadian rhythms, specific conditions known from living organisms including plants. Open for discussion is a 5-hit working hypothesis, attempting to define key elements involved in injury progression. In essence, although abundant biochemical mechanisms are proposed for the initiation and perpetuation of liver injury, patients with an alcohol problem benefit from permanent alcohol abstinence alone.

Recent advances in understanding liver fibrosis: bridging basic science and individualized treatment concepts

Hepatic fibrosis is characterized by the formation and deposition of excess fibrous connective tissue, leading to progressive architectural tissue remodeling. Irrespective of the underlying noxious trigger, tissue damage induces an inflammatory response involving the local vascular system and the immune system and a systemic mobilization of endocrine and neurological mediators, ultimately leading to the activation of matrix-producing cell populations. Genetic disorders, chronic viral infection, alcohol abuse, autoimmune attacks, metabolic disorders, cholestasis, alterations in bile acid composition or concentration, venous obstruction, and parasite infections are well-established factors that predispose one to hepatic fibrosis. In addition, excess fat and other lipotoxic mediators provoking endoplasmic reticulum stress, alteration of mitochondrial function, oxidative stress, and modifications in the microbiota are associated with non-alcoholic fatty liver disease and, subsequently, the initiation and progression of hepatic fibrosis. Multidisciplinary panels of experts have developed practice guidelines, including recommendations of preferred therapeutic approaches to a specific cause of hepatic disease, stage of fibrosis, or occurring co-morbidities associated with ongoing loss of hepatic function. Here, we summarize the factors leading to liver fibrosis and the current concepts in anti-fibrotic therapies.